SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '51d20083665e3664f1f9a0d4374637107af1c7fb579eeeb4bdf3273f70e6b98a' 
  AND token = 'YypfE+3BF0RgRun3EZAGHcx6yAN4IQKqwvths/gdZ5I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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