SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16b81eb1f29970a85a0285ea125617fd1abc26564611b81e996278b1436601be' 
  AND token = 'qnVSmpzrj+9BdiU0GKuiqKRRbsGOlBwSqA/UmTHP7hQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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