SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0b39606efc5881fd475254a5b7db23f0f3a6d442e7937f20a66cd566fbb3a970' 
  AND token = '+JLgPwSoTfU/nduiFB/3Qr7Rm8M6C2VRDUlk3LkYVLs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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