SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '592452acb502c6c003b88fdd795a0402aacf8120b2ef7c2a1efe75a4cdf64789' 
  AND token = 'ZhrjxN7AfyQzQXglG/JpKL2r1NZYRgnUi/NffPUmyBA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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