SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92fc5e1530df81e142e88f551817221f873e28aabbfc434b8d0d393978d7e1c6' 
  AND token = 'LVH0RshjrRBYjBrtxK9bRknvvBRiFhRRMRNrTmowvi0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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