SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '823c0133304f2992edfc5a97556127da11cc193d81bf2c317462a604410a2c01' 
  AND token = 'KnnokV3MKniDb/cElFzWwSm9AaGHp1pZ1szlX56ORPY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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