SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c8d42dee152987e621ec0020d072b92d625b63daeb35e063a6c2f9886d3b00e' 
  AND token = 'bQ5THzI25fCXMxiPUjIdBiRI0ciTV+3K5yHUBumQ43k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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