SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18ffb618e10e18b0c3402486cc24ecba4795b9cc93fea546bfcb406a0db74516' 
  AND token = 'lZvgdezjQd60VzMpjOifZVM7GPDVGHj/gssCr/ussYs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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