SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aff940180edc7ebf2fd37dea094a86d4a6f554c892ec529d9b2a61b530b87368' 
  AND token = 'qQmGaJq/Ujb+VSRN7uNxXz2glz8aK8Z7LSAL4zvMwDg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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