SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff00bd6470241e40661637d5641f8b6fec3e4cac828b116fc556001484e374ac' 
  AND token = 'kpU8V+1fAVQ0Oq629JaUPTiS3mlzKA4IPr8jpLepCKw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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