SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb0fbc581e60d725d2ec2716fc29015bfa0861335d88adc8f66554dda0a408f4' 
  AND token = '+XtuJItlneYlC3+Wuqs2sK+2olK+tIYzmrqc++SzVBc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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