SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16f6405a0b7b73a33dcdd3b0462520e77719eeff54c07ee011604ded50b5be4c' 
  AND token = 'eRJyXH6zIZQg7thlETjASuiYJJuaxyKaYo5E2j7U5Q8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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