SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1c7249d55be89efd159870820bab529f5afd0339a79800e8499e077d8938159' 
  AND token = 'OaKxZLbYX2iInfLV/acabp4mTcdIB6b9VCVUe8Boh68=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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