SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e627be40a233f71971d2f995796d448da2df2165cb98f28b87f292e3315a75fc' 
  AND token = '6vZpTojKxgAMB0b4SjDtqHCM/Yo43qe5CUrfEAKWrIM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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