SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '242ed191cbc9839ac1f622ef934a5ecf02b9a3c8515469ef475704bb71cd541d' 
  AND token = 'zGC/ICSqHO/Q7A0DhvQpAlPN9aUmTSCq2+I2TMgFR/Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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