SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5102d135eda416e0b85c3f1001cd09ecf8c129094e845af643c335ac649b730e' 
  AND token = 'gmbr6fBr/GrRrkUG5xtE4n+dfXVBgVcdzsRMdQPSU9c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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