SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9350489bd3d423f4445e5b493d4262795b659825fc71dfa6d17300b24391a403' 
  AND token = '+iiH1U72wTqy2ogEKuuWvJxlD6M6ApDKmuaIBX2TQpY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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