SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'f6e375cde74ab741f3a01c66bae935462933590226e9078b3927e9bd856743ba' 
  AND token = 'HdEBffuj6PDi3bpld+sFmG1VFuCXxDDid7elgbp2t/c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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