SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83c516366e19ed93bbb72234c1bd154a546b5783741e0ae9cf76219f3835e3b7' 
  AND token = 'FfpRs5PVOtZFYBCR/FjNvRJz28giFTCsYXJv1jQpYe0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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