SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'efafd851dc19434187e276a85c5f0e4f634356c3ef0aa64a071bea710447ed1a' 
  AND token = 'FbvkAsI7wfHyA4BHK2BMF2j6usZBCysQmQsaDscoRO4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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