SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '548372a612947d108c62b46e230924e6d73e384fb362b1b083fba18443177e8c' 
  AND token = 'MA5ypTeKNjqlfUtw3Pyx5TrRHdKOAyJwKOtsnZ+9/hY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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