SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '138bbb056ef09b09c31fc535b14175866778365a0a37e2837bcba2418c4aa9e4' 
  AND token = 'QtJBivqONa79aCKGHRObRKXa8sSBFdWmYXgiKyaDNE4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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