SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b8cbbf582fddb848388de3f7b824ecc223fba58260a6cc5e3ecfb029674f4b1' 
  AND token = 'e8bB1T3zRNApzD/ybScF4rskpDDXvXxHeAuh+YFaAL0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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