SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '308e8d3179932b090936275892f844957f4aa3472208c4bbb39548d9fcf3a324' 
  AND token = 'zEMl6MGkmPuGXlrBoUXlsqZXoFaxJj3rzINJfBf/i0s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00061

JSON explain

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