SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9ec8a76cf86c1ac0ca1ea917f73de5abe3426ef94206e51594cddd41b776cf0' 
  AND token = 'asd0ujWotAZym76ZIb/X6KLkleflGE6wRT7JR0KYTOs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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