SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18a8eb8b888e9760dde89710ffbdead136b10b168728691637f8eef002650541' 
  AND token = 'uKHmLSdz++bPVqFzno9QLXIrmFlxL/LzHzYhJ3x042I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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