SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a05693fcaf4c28eec3cae016d78dd0add3a8fc5c0f9a74501b04315273d39a8' 
  AND token = 'OiuTIbRG/RBk8psjxrAZlfo1Kql1wvmZg5KhKquN+Kg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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