SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79c6ed54855cf48d99f8ed64f23b738f9b82705bcb4d93691941cf0b29980e85' 
  AND token = 'zCm4MLM9g8gBJ3hqh7dTm3+wmVBwBVhL8+sDGiR1QzQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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