SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb0ccb8a960f1b11466c25aaa9404a1af2074fde6c15165a724f9390301c5e98' 
  AND token = 'FUQdSWO/1PUycdnTOshGMEhf+9JZpXovJK4cyGkL4NE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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