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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '065b0fc4cfc2c43274734c33944c7e0c1af775f301d1e9f9ecca94ecbdae4722' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00793

JSON explain

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