SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f26f4256634305ff93dae351766a85dc2b734303510a00778015cc172bd73a62' 
  AND token = 'u1rLygdsBuu9ZstPOpZ3D/S2T1MLXQnXylHRgptVFHY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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