SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6379ee54b15db7640903f051e5acc824ff2e183e8be3c6696c033faa908f85b' 
  AND token = 'K74EpycvzqSuU+U17K7JD4wAbAxK+P1uIwhGjrWpwPQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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