SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53e75df50a2e01ccf47fa002caef8ffbc22f47dcf6c5ad6c15eebcd32bfcf056' 
  AND token = 'jmN/6/47a6+H/CyMjJolFFgrfAjXvTTPhKqSGjcAoCk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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