SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd403b11b3633267b98684b968314db67c3991027ed11700399defe58016c1965' 
  AND token = '4QcEO+a5TGewEMTriDdHsAcWq+c0/I30ZXPRs7zpbOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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