SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52d17b72b97836b984fbf23f28781982e25c274aaeb1c2fcc399abef05e81c8c' 
  AND token = 'DxFmnGlj3IXt5Z673zslfJqMYeRx+/J7sCoHeI5OHNA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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