SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2ece892828839e991f58e35fb5b9358ec0d62c9b62043c8e2e604861aea1f42' 
  AND token = 'tx8cqW5/ojBNrJGcq/4q7goC/mmwFA4lsTQWL4+STX4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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