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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3ee9bb2370ccbd015ef846cbc228155329c1a838e7e908db1a84c33fe375d89' 
  AND token = '7zqJ1BQPrRQWvPkbf4PbnfXTRfdT57pm2NC6SCTD62I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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