SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1f3bcd8393edaf19b00fcf125e396d81023cf3d03aa437647bc784fa434a70c9' 
  AND token = 'qson/b9+BUdE/7CZDKZtRhVNbOFZ8A0qtqSwYM+DzmU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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