SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '84104e4134582bd065bc812457fd18b345f4756c8295230cc5f623dfac2be53d' 
  AND token = 'yMDSRrUjhp2JCh+3gb+x1qLGd8FTV7mVksMtNO07De0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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