SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '5952adf94997e0beea03d957969fb6e1e8fe04ee49a985a523b14d920efc2786' 
  AND token = '8B/xgDZvKZJfr3zIeKZG1VdQPrBJrY5b8DtdbU+1jJE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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