SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55b92088d710da5a286b20348021de372be84a35313e401f35a63a03e1ac403d' 
  AND token = 'NTdxdgoCJ7xM5JwMeceS3cFDUR2cyhjydCgN6joMKqE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}