SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db6a3f867931405547bace3943d32b720c8e2f6f4283a6e781d706f57e4adfba' 
  AND token = 'zdKUMVQDfPKC7cJYsUgBbcUGFU4YHOOqAfUHa17H4mc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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