SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '247e1793ec631548d1ec94b1ed4ebea95ff3a3819136292d0cdb35ca5f898308' 
  AND token = 'BAqsRKSzuK+dC0h60Gl8Ya8zRtSyZ0euS3s13Oj16VY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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