SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '306a8f96e25ed7bbec1b84d71655421174a2fc4da8fb464a0682158d92c8d709' 
  AND token = 'oippmjR/plY2OVeq1FyVZBUjoHzU/p6uFFouxD4YzxM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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