SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0f4fe92e82a0adce84f27715c799d9bbbe05e66791ea954ee2013c2a1ce1ada' 
  AND token = 'SxBmrtGDcpEVeRBMzu3feJwpzhQh5gEqYbFIPwBrf0w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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