SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3b34924cfd39ea75e42839c24e67a3a8af4094602e61d843c5f2453f77f8173' 
  AND token = 'eKHXJrQU4BiU4sHbf89OHAJs7DwJxZ8JgCuoJVJm/jY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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