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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c2c12715bb613baa6cf9ff9f50e0aa7e8cb6b00920452e5da5fd4f6e5dc15f8' 
  AND token = 'TZxnbcFxPdWGFwTmg3EH3+Zf76SmanFsMSS+qShyi2I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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