SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '490a1293513fc86490f84d89aaad55978ad3000c736ddadf4d22947ac0e7261e' 
  AND token = 'eV8u6Lk/jGvMfS+vtnXNLzUqFq8pGNCRMrCwA4w5VLQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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