SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a34781d2067abc61ccb0a75e712d129c13fc068bf3894dbe2d09febd2b04d34' 
  AND token = 'wH3ZN2+UBQVYWrFrC40u7XC9A5/fsMNAGvFMiUfjJn0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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