SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7c728797fac6897bbfc82d9653b7940caebcbe33f6e1fc15673e1fd06bfa58a' 
  AND token = 'S7HZgdv/O8AEPair/J5k8iTg+aIhwliHGPQjBZoqLwI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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