SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f905635332d484a30a34ee3fd3b86566966af032dec3fb070a27d1a0b6e1bbe4' 
  AND token = '6JUBXDUwQcxTkzxjCeksOxPmosd0zjgrmCiThuUHqao=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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