SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be96ac3b8f3cefbc0f4f10f90bc9c47de902f7b51bc728c39412fa8816eb3d5e' 
  AND token = 'N7+D/qVBcgcGW7XRkYo9xSwZ2tlF+LKCC4asfmfzuI8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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