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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d5e000504f88bb84eb1258eb2780cb4b1e6c3a1f76e9ec8fed0aa65f9ddb2da' 
  AND token = 'Kcsxd0tHqie2/BBpP+jrbDG48plvZdaPn+Y4UrMn2Ns=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}