SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2f6410783911240496872d06c278fb25f44e072389317ed1b99d001d3fb73cd' 
  AND token = 'ITYg/s+oNaRvd2lwo7xS/q2O+xPVDYCFEg/zSCwwTwY=' 
  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"
    }
  }
}