SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc4a48a1fafaad291b1892420f84bd0e19e2e6e53b7beae3b95ff34cf73df0cc' 
  AND token = 'klJzeDVEu1+3BnicKnNmiHvXIsywXlmXc311pJAftPo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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