SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ce40ef3a59965894cf380350e30708ecdb4d1fad89194382c752f665f7a0e3a' 
  AND token = 'ICFGqSrCXDyUI4u4icv+JOy2QwdnjJQ3wjbx6R6UfBs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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