SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87bc99bac15c0fe54a4dc9780ee973e19fd19922b1520c413100852fc58be671' 
  AND token = 'N/okpcwqlmNg6D1HDGb/Vx90msigCYoNy8gRmwHnYso=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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