SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71bbdfbde93e67fafc6262a58be96a5980001ee3ebff8837906d91e6c6bdfd9b' 
  AND token = 'clJfcKTKcnJ2i/RbJMM7pTlLiFfcSTpfFD2GSD4lphc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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