SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b1e71d39a643523d8cc8d2959a75a0151c1eedc9356ed3fd4bf4e3e59b70139' 
  AND token = 'wxw2luCa2dodh7BglubiwxcPjp872iHTIBNuEKG0IxI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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