SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '209b63cc8f216acc5577bd66314aaeb56c8fd08ee562d1f0278af3b09895a177' 
  AND token = 'XV1y9AwU5WlCly0DhDFb9cEWyvu/vvWRHXZCm47w/s0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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