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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df4d1176e28c9451927d743c8fe39fdbf3f7e65ad9e6e2e90960a6abbc61cf79' 
  AND token = 'zE4f3fDE4N8+20XmhRRzebNorwFCFUGrWMdkmpL9SZs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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