SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7dbf2ca470788711397eabce1e20bfdeb5cf258efc55392ea7e9bac2d69b8a64' 
  AND token = 'TnUkfSAGw6gKh1BY/TFK17S+CixMN8yZWwSbjOxhjMs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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