SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '02682a4ee32c22d9bf644f2b14bc62b0feb2da58c40cc30d349335ce268aecb0' 
  AND token = 'DGymoUIR3EM2u4RHcKdqZpkceMqjLVgxbD7e4g03vKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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