SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a97290803d41d1a213c08ab37194b094dd2d6f72136d4d7fa398f8c42b621c33' 
  AND token = 'KxzKpdg4yOMMink8pl/WwVtkaavNZ9PGT+BHUVmnQTs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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