SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1da979f4073496101759e010133ffa8c49e3444e44f11293a05baef54434d2f3' 
  AND token = '/k7+cR++6WXh2IEddxjohRTmjXvIRPxpt2RrtzW4yCQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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