SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eefa3b2709c0f56f2e9305200f45c539bdfa3626ef9bb0d42d57500d84f6d4ea' 
  AND token = 'PuHz2fOxW5QNUb327wNMtEhr5upedhatnlexg+wh4So=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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