SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87eccd3a0e344b9445bcd2466166b79980aaab2929c07bc039ba2f987863fe7c' 
  AND token = 'z5OYHsLcduAAMzlph4jP+rlI1BIhFX0oLL2oYS/qWgU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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