SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e00c3ff85f5c502d8eba49df6d367747a1450b80a2d94f3ea300ad26fffd4d4' 
  AND token = '1rshnSdRli7mgSRbPKFMQ+QHAqS4GRT2vIjP+YC0C7U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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