SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c2e3d2343b28a843c37e91cec21c3257eae629584f770cda6c4fa25e29628a5' 
  AND token = 'UqaB1Rab9m2+SLdFVgaLTjCQYDrRfAhR8oXvwcucv+s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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