SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b621ed65eaaaf55b13cda0c5c00c9acebb94358e4d25a93a4d047f795677ac7' 
  AND token = 'tXUwDijYJD667l/YiRKWrp7PFMCyZ9utBuU27VfhsAk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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