SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75f7c518dc8551a2acc9fe3228d39c8ea3eb650ccc72995f6fe8d65b8ee91be4' 
  AND token = '/zwhQ5xrBSE5ydUttL/pJ+YPPgKhnHDMN8BOviF6ILo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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