SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7fb51f91f9eea03535da5d2593547376799678baecb1fe585d50bb01ea3b9315' 
  AND token = 'nhAaltB7wJM5MvBmm9JBEum/ibw25S0fufYdoCSW608=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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