SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18c71066debe8effdf2328137eb553915db7f9e9b450038dea7204dea083479a' 
  AND token = 'XKLHjZGccPzGNNzj4B2RtEgfCU9MIECC/J4sRzdqhBc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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