SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac031e7799641d8e99d7fc6f64dc6a00bc8455af794fc209c34e379512bbef02' 
  AND token = '2Nu5r0NHwYYR+5oZ26661qv6oUEDqo2EUip5tJeCXtA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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