SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7437ffaf4482dc4588e92030ee7a957a27f55300e994f12bf9e8f52d38d241bd' 
  AND token = 'PXL4ZfHfCpKRtKgfGZORBozvbIflaqyblM8uR2uFFI4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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