SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '751dce44a6d78bfa14bcf5ee0c527cb20c467edfa3ee3c6cf824a415cdf78717' 
  AND token = 'G9vP90YPIilahgEtsnnJPzZmOJDmXtTdIXt1xbuTvS0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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