SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc21a067b73a5db16bc0762a48f0e65c651646f7ad35e386c922539612bdd4e1' 
  AND token = 'HKGIVChq3sEHm6L+ee83RNVLSbBRTRu81Aca547Tels=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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